 Squadrons from MAG-21 fought at the Battle of Wake Island, Battle of Midway and as part of the Cactus Air Force during the Battle of Guadalcanal but the group itself remained at MCAS Ewa until February 1943 when they departed for Banika in the Russell Islands.By June 1943, MAG-21's squadrons were fighting large scale operations against Japanese installations in the northern Solomon Islands.The group moved to Efate in November 1943 and remained there until June 1944.